This invention relates to electrical lead-through installations, and more particularly to electrical lead-through arrangements for applications where large pressure and temperature differentials are present.
In various apparatus that are currently in use, electrical conductors are required to pass through a wall having large pressure or temperature differentials, and it is necessary to provide an effective electrical insulation around the conductor, as well as sealing against heat loss and pressure loss around the conductor. An example of apparatus in which this presents a problem is a turbogenerator with a superconductive excitation winding, such as that disclosed in a paper entitled "Turbogeneratoren mit supraleitender Erregerwickung," published in "Bull.Sev" 64 (1973) 17, 18 August, pages 1040 to 1050, in FIG. 3 on page 1043. The excitation winding is cooled by liquid helium. The cold rotor body carrying the winding is located inside an outer, warm cylinder, and a high vacuum is generated in the space between the rotor body and the cylinder. The mounting of the inside rotor body and the transfer of torque to the shaft ends, which are at room temperature, is accomplished by thin fittings which are cooled additionally by means of helium. A helium carrier, rotating vacuum seals and slip rings are located at the non-driven ends of the shaft. Lead-in wires for the excitation current are arranged inside the shaft and passed from the high vacuum chamber into a chamber containing the pressurized helium. Lead-through conductors are mounted in ceramic plates which separate the high vacuum chamber from the low temperature pressurized helium chamber. As a result, the mounting arrangement is subjected to high stresses because the two chambers have very low temperatures and are under dissimilar pressures. Also, the lead-through conductors are subjected to centrifugal forces as the rotor body rotates.
Accordingly, it is an object of this invention to provide a mounting arrangement for lead-through conductors which is capable of operating properly under conditions of large pressure differentials and temperature differentials and while subjected to centrifugal forces.